(1) Field of the Invention
The present invention relates to lower density single crystal alloys that have particular use in turbine engine components.
(2) Prior Art
High rotor speed turbine engine components, such as turbine blades, require materials with as low density as possible while maintaining reasonable levels of high temperature creep-rupture strength. Alloy design philosophy has previously been to achieve maximum creep capability without undue regard to alloy density. New engine designs require that extremely high levels of performance be achieved, which can only be met at very high AN2 conditions where A=Area; N=Rotor speed. This in turn necessitates a new look at alloy design philosophy. For advanced high rotor speed designs, turbine blade weight (density) is critical to minimize the blade pull on the disk and thus minimize the overall disk size. Current second generation single crystal alloys with densities ranging from 0.312 to 0.323 lb/in3 are widely deployed in production, while third and fourth generation single crystal alloys with increasing strength capability have correspondingly higher densities ranging from 0.324 to 0.331 lb/in3. If reduced alloy density can be achieved for a given level of creep capability, significant savings in engine weight and increased engine performance would result.